Study on offshore wind farm repowering strategies in Hong Kong

In recent years, with the approaching end of service time of the first-generation offshore wind farms, the high decommissioning cost has attracted more and more attentions all around the world. To decrease this huge cost, some repowering strategies have been presented and studied. In the repowering method, the original wind turbine (WT) foundations will not be dismantled immediately after their service lifetime but still work, the lifecycle of these foundations is extended to two generations WTs’ service time. To promise the structural strength of foundations, the second generation WTs are supposed to be smaller or some strengthening measures should be adopted. During the whole two generations’ service time, the costs of removing the first foundations and installing the second foundations are saved. The levelised cost of energy (LCoE) is regarded as the criterion to judge the effectiveness of the layout of the wind farm. The aligned layout is analyzed in this study. As for the wake effect, Jensen wake model is utilized to calculate wind energy losses. In the repowering strategies, the decommissioning cost, which is a critical part to estimate the LCoE will also be introduced. Finally, a case study in Waglan Island seawater area in Hong Kong is analyzed and discussed. The results demonstrate that Hong Kong is an ideal region to develop offshore wind power and the repowering strategy is practical for cost-saving. According to this study, the LCoE of an offshore wind power farm in Waglan Island seawater area can be decreased to 1.06 HK$/kWh.